Dysbiosis and reduced small intestinal function are required to induce intestinal insufficiency in mice.

Extensive bowel resection can lead to short bowel syndrome and intestinal failure. Resection-induced dysbiosis may be related to the specific anatomic site of resection and influences the disease progression. While patients with end-jejunostomy are at high risk for intestinal failure, preservation of the ileocecal valve and colon counteracts this risk. The present study investigated the role of the cecum in maintaining microbial homeostasis after different types of small bowel resection. Male C57BL6/J mice were anesthetized by intraperitoneal injection of ketamine/xylazine and received extended ileocecal resection (extended ICR), limited ileocecal resection (limited ICR) or mid small bowel resection (SBR). Stool samples were collected before surgery and between postoperative days 2-7, for 16S rRNA gene sequencing. Only extended ICR, but neither limited ICR nor SBR, induced intestinal insufficiency. α-diversity was reduced in both ICR variants, but not after SBR. All resections resulted in an increase in Proteobacteria. Pathobionts, such as Clostridia, Shigella, and Enterococcus, increased after SBR while Muribaculaceae, Lactobacillus, and Lachnospiraceae decreased. Limited ICR resulted in an increase of members of the Clostridium sensu stricto group, Terrisporobacter and Enterococcus and a decrease of Muribaculaceae. The increase of Enterococcus was even more pronounced after extended ICR while Muribaculaceae and Akkermansia were dramatically reduced. Both ICR variants caused a decrease of steroid biosynthesis and glycosaminoglycan degradation associated pathways, suggesting altered bile acid transformation and mucus utilization.